CN111108301B

CN111108301B - Coiled spring and coiled spring arrangement

Info

Publication number: CN111108301B
Application number: CN201780095015.2A
Authority: CN
Inventors: 拉尔夫·格罗斯科普夫; 尤金·克鲁斯
Original assignee: Wabco Europe BVBA
Current assignee: ZF CV Systems Europe BV
Priority date: 2017-09-21
Filing date: 2017-09-21
Publication date: 2021-06-22
Anticipated expiration: 2037-09-21
Also published as: EP3685068A1; EP3685068B1; US11384808B2; US20200217380A1; CN111108301A; WO2019057264A1

Abstract

The invention relates to a coiled spring for locking an undesired rotational movement of a rotating element. The invention further relates to a readjustment device for readjusting the wear of a brake lining of a disc brake. The reconditioning device includes: a guide sleeve in which a coiled spring is arranged; a slotted ring surrounding the guide sleeve, wherein the slotted ring is coupled with the closure cap via a torsion spring; and an open annular member surrounding the slotted annular member. The invention further relates to a disc brake for a vehicle, in particular for a commercial vehicle, wherein the disc brake is provided with a readjustment device having a wrap spring.

Description

Coiled spring and coiled spring arrangement

Technical Field

The invention relates to a coiled spring for locking an undesired rotational movement of a rotating element. The invention also relates to a readjustment device for readjusting the wear of a brake lining of a disc brake. The reconditioning device includes: a guide sleeve in which a coiled spring is arranged; a slotted ring surrounding the guide sleeve, wherein the slotted ring is coupled with the closure cap via a torsion spring; and a split ring member surrounding the grooved ring member. The invention further relates to a disc brake for a vehicle, in particular for a commercial vehicle, wherein the disc brake is provided with a readjustment device having a wrap spring.

Background

A hold-down device having a readjustment device for readjusting an air gap between a brake lining and a brake disc is known. In general, such disk brakes can usually be actuated pneumatically or electromechanically.

For example, in the field of commercial vehicles, there are mechanical readjustment devices for the disk brakes of commercial vehicles. In disc brakes, the holding-down device has the task of providing a uniform air gap in all driving and braking situations, which in turn requires very high precision in the readjustment. In the case of a brake actuation, the existing air gap must be overcome by the hold-down device until the brake lining bears against the brake disk. This air gap is decisive for example for the pivoting range of the pivoting lever used for the pressing and thus for the maximum braking force or the braking force reserve to be applied. If the air gap differs from the target value in the case of a braking of the vehicle, the readjustment device is actuated. In other words, the brake lining is automatically adjusted by means of the readjustment device in the event of a deviation from the nominal value, that is to say an increase in the air gap due to wear of the brake lining and/or the brake disk. The adjustment can be performed, for example, by an adjusting movement of the pressure plunger.

Coiled springs (Schlingfeder) are in turn commonly used as clutches or overrunning clutches. In the field of commercial vehicles, coiled springs are used in readjustment devices, in particular in disk brakes. According to DE 102014218233 a1, a wrap-around spring clutch is formed by a helical spring wound around a shaft or a cylinder, which is fastened on one side to a drive. By moving the ends of the coil spring closer to or away from each other, the frictional resistance between the coil spring and the shaft or the cylinder can be adjusted.

DE 102014017430 a1 discloses a wear readjustment device for a disc brake, wherein the readjustment device has a wrap spring which engages with an external thread of an adjusting spindle at least when twisted in a second rotational direction opposite to the first rotational direction and screws a readjustment gear relative to the adjusting spindle.

EP 3051170 a1 shows a readjustment device for a disc brake having a rectangularly shaped coil spring, wherein the coil spring is arranged around an outer piston and one end of the coil spring is connected to a drive ring, whereby the coil spring acts as a one-way/overrunning clutch.

In DE 102014101341 a1, the transmission device of the readjustment device is designed as a helical coiled spring, wherein the readjustment device is supported radially relative to the drive element along a first helical section and radially relative to the readjustment element along a second helical section. One radial support is located on the inside of the wrap spring and a second radial support is located on the outside of the wrap spring.

DE102014019111a1 discloses a readjustment device with a coiled spring, wherein the coiled spring is held in a rotationally fixed or rotationally fixed manner relative to the adjusting screw and/or nut part. The coiled spring is in circumferential contact with the adjusting screw and/or nut part and is formed from a plurality of coiled wire springs.

A further readjustment device is known, for example, from DE 102014017438 a 1. The readjustment device has a wrap-around spring with a projecting spring end, which engages in a retaining opening of the guide sleeve or surrounds the trailing side of the guide sleeve in a wrap-around manner in the circumferential direction. Thus, the wrap spring is positioned axially fixed. A distance or play exists in the circumferential direction between the guide sleeve and the projecting spring end of the wrap spring, which cannot be compensated for when the brake lining is readjusted by wear.

Disclosure of Invention

The object of the present invention is to overcome the disadvantages of the prior art and to provide a wound spring and a device for a wound spring arranged on a readjustment device for a disc brake, which prevents premature fatigue fractures and ensures an acceptable deviation of the switching angle (Schaltwinkel) or dead angle (Totwinkel), that is to say the switching state of the readjustment device until the wound spring is in slip, and an accompanying acceptable deviation of the air gap of the disc brake.

This object is achieved according to the invention in that the wrap spring has at least one U-shaped projection.

The U-shaped projection of the wrap spring is used as an additional radial support in the installed state in the readjustment device, whereby the load acting on the wrap spring is significantly reduced. So-called fatigue fractures in the coiled spring are inhibited or at least minimized. Fatigue fracture is to be understood as an overload of a material, which occurs when the stress in the material is too great or when the pressure exerted on the material is too great.

In a further advantageous embodiment, the U-shaped projection is formed by at least one coil spring turn between a first coil spring end and a second coil spring end. The coiled spring is therefore substantially more resistant to bending than a design with a U-shaped projection at the first end or the second end of the coiled spring. In addition, it is not possible or at least more difficult to bend the U-shaped projection, thereby preventing an increase in the switching angle. Thus inhibiting premature failure of the reconditioning device.

Furthermore, the wrap spring has an angle α between the U-shaped projection and the wrap spring first end in a circumferential direction of the wrap spring.

Furthermore, the wrap spring extends over an angle α of 90 degrees between the U-shaped projection and the first end of the wrap spring in the circumferential direction of the wrap spring.

The loaded first end of the wrap spring is continued so that the switching angle is halved. In particular, the coiled spring continues the angle α preventing a lifting of the clipped end in the readjustment device during the return stroke of the readjustment device.

In a further advantageous embodiment, the wrap spring has a circular cross section or a trapezoidal cross section. In contrast to the original shape of the wrap spring, which is made of a rectangular wire and is tensioned to the cylindrical peripheral side, the wrap spring extends in the thread of the adjusting screw with a circular cross section. By using a trapezoidal cross-section instead of a circular cross-section of the wrap spring, the fatigue performance of a wrap spring made of wire material can be improved again. However, the trapezoidal cross section has the disadvantage that the stiffness of the wrap spring and thus the tolerance sensitivity is increased.

The object is also achieved according to the invention in that the wrap spring is arranged with a U-shaped projection on a shoulder (tucke) of the intermediate ring. The arrangement of the wrap spring on the shoulder of the intermediate ring prevents play of the wrap spring between the guide sleeve and the intermediate ring. The coiled spring is clamped without play at least in the initial position of the readjustment device.

Furthermore, the wrap spring is advantageously arranged in the thread of the adjusting screw. This increases the accuracy of the readjustment process and eliminates the need for components such as the circumferential side on which the adjusting screw has been tightened up to date.

In a further advantageous embodiment, the wrap spring is supported in the circumferential direction on the trailing side of the guide sleeve opposite the free-running direction during the readjustment process, and the readjustment bolt is twisted. In the return direction, i.e. in the free-running direction of the wrap spring, the intermediate ring serves for positioning the wrap spring.

In a further advantageous embodiment, the rotation prevention element of the threaded ring, the U-shaped projection of the coiled spring and the groove of the slotted ring are arranged on one side and on the same side of the adjusting screw, so that the assigned force pair is obtained. This reduces the lateral forces and moments acting on the readjustment part, such as the readjustment bolt and the inner sleeve of the readjustment device. Additionally, the effect of the clearance of the outer diameters of the guide sleeve and the thread on the air gap is minimized.

A further advantageous embodiment results from the fact that the rotation prevention element of the threaded ring, the U-shaped projection of the wrap spring and the groove of the slotted ring are arranged in an angular range of 0 to 45 degrees from the axis of the wrap spring. The displacement of the adjusting screw in the thread of the pressure piece is largely prevented, whereby an increase in the air gap between the brake disk and the at least one brake lining and an increase in the deviation of the air gap are avoided.

In a particularly preferred embodiment, the rotation prevention element of the threaded ring, the U-shaped projection of the coiled spring and the groove of the slotted ring are arranged one behind the other in an angular range between 0 and 25 degrees on one side of the adjusting screw and on the same side. Thus, transverse forces and transverse moments acting on the readjustment part, such as the readjustment bolt or the guide sleeve, are almost avoided. The clearance between the guide sleeve and the adjusting screw becomes inconspicuous in terms of tolerances.

Furthermore, a wrap spring for readjusting the wear of the brake lining can be arranged in a readjustment device for a vehicle disc brake.

Drawings

Selected embodiments of the present invention are explained below with reference to the drawings. Wherein:

FIG. 1 shows a front view of a coiled spring according to the present invention;

FIG. 2 shows a readjustment device with a coiled spring inserted on the adjusting screw;

FIG. 3 shows a cut-away side view of an adjusting screw with force flow of a readjustment device;

fig. 4 shows a schematic view of the force flow of the readjustment device;

FIG. 5 shows a partial view of the reconditioning apparatus with a coiled spring in detail;

FIG. 6 shows the arrangement of the wrap spring on the adjustment screw;

fig. 7 shows a disc brake with a readjustment device in the installed state.

Detailed Description

The wrap spring 1 according to fig. 1 has a wrap spring first end 2, a wrap spring second end 3 and a wrap spring section 4 arranged between the wrap spring first end 2 and the wrap spring second end 3. The coiled spring section 4 is divided into two coiled spring turns 6, 6 a. The first end 2 of the wrap spring extends over 90 degrees in the circumferential direction. Thus, the switching angle of the readjustment device 10, not shown, can be halved compared to the prior art. The first coil 6 of the wrap spring has a U-shaped projection 7. The introduction of a load L on the U-shaped projection 7 causes a bending moment on the U-shaped projection 7, which deforms slightly under the load. As a result, a radial force is formed on the side of the U-shaped projection 7 opposite the load introduction L, which radial force prevents further deformation and limits the bending moment on the side of the load introduction L.

Fig. 2 shows how the wrap spring 1 is arranged in the installed state in a readjustment device 10 of the disc brake. The wrap spring 1 is fastened to the guide sleeve 12 via a U-shaped projection 7, which is a suspension that is prestressed by a spring, wherein the prestressing of the spring is effected by a torsion spring 14 on a slotted ring 13 and an intermediate ring 17. Furthermore, the readjustment device 10 has a disk spring 8, which axially pretensions the threaded ring 23. The disk springs 8 are arranged between the pressure piece 9 of the adjusting screw 18 and the threaded ring 23 and below the threaded ring 23. Subsequently, the intermediate ring 17 is pressed with the guide sleeve 12 in a form-fitting manner. During the readjustment process, U-shaped projection 7 of wrap spring 1 rests on the rigid mount of guide sleeve 12 and twists adjusting screw 18. In the return direction, the intermediate ring 17 serves for positioning the coiled spring 1. The split ring 16 enables the resetting of the readjustment device 10 during the replacement of the lining, in so far as the coiled spring action in the locking direction SR opposite to the free-running direction FR is eliminated.

The readjustment device 10 has the principle of the associated forces (Actio and Reactio). That is, the groove 22 of the grooved ring 13, the anti-rotation 24 of the threaded ring 23 and the suspension of the coiled spring 1 in the shoulder 20 of the intermediate ring 17 succeed one another on the side of the readjustment device 10 in an angular range 25 from 0 to 45 degrees. The reference point for the angular range 25 is the wrap spring axis 5 of the wrap spring 1. If a force F acts on the first groove flank 27 of the slotted ring 13 via the readjustment pin 28 of the swivelling lever, not shown, this force F is transmitted directly to the wrap spring 1 via the follower flank 21 of the guide sleeve 12. The slotted ring member 13 also has a second slot side 27 a. The friction torque in the screw thread 29 of the adjusting screw 18 and on the threaded ring 23 is the same. As a result, approximately 50% of the force F is generated at the anti-rotation portion 24 of the threaded ring 23, which is transmitted to the U-shaped projection 7 of the coiled spring 1. The anti-twist portion 24 of the threaded ring 23 resists the reaction force FN of the anti-twist portion 24 on the U-shaped boss 7 of the coiled spring 1. The circumferential force UF on the coiled spring 1 and the reaction force GF on the anti-rotation section 24 of the thread ring 23 likewise form a force pair of opposite (unequal) forces. All "teetering" is thereby eliminated and the clearance between the guide sleeve 12 and the adjusting screw 18 becomes unnoticeable in terms of tolerances. "teeter-totter" occurs when the readjustment pin 28 of the swivelling lever drives the slotted ring 13 via the slot sides 27, 27 a. Then, the slotted ring 13 first moves like a seesaw, and the coiled spring 1 is carried along after the gap between the slotted ring 13 and the guide sleeve 12 is passed.

If the reaction forces GF and F are equally large at the anti-twist portion 24 and at the point of action of the readjustment pin 28, that is to say on the groove sides 27, 27a of the slotted ring 13, an imaginary axis of rotation will be obtained between the point of action of the readjustment pin 28 and the anti-twist portion 24 of the threaded ring 23.

According to fig. 3, the reaction force GF at the torsion prevention means 24 according to fig. 2 and the force F at the point of action of the readjustment pin 28 according to fig. 2 differ in magnitude. The rotation prevention means 24, the readjustment pin 28, the disk spring 8 and the threaded ring 23 are not shown in fig. 3, so that reference is additionally made to fig. 2. The instantaneous center is thereby shifted into the interior of the adjusting screw 18. The instantaneous center is to be understood as the instantaneous axis of rotation. Additionally, the forces GF, F of the force pair and the first thread 32 of the screw flight 29 are not axially in one plane. Thereby creating a bending moment about the transverse axis of the adjusting screw 18. As already described in fig. 2, the disk spring 8 is axially prestressed. The adjusting screw 18 is clamped against the nut thread 35 of the pressure piece 36 by the pretensioning force of the disk spring 8 on the threaded ring part 23. Due to the fact that the profile angle β of the flank 34 of the screw flight 29 of the adjusting screw 18 is 60 degrees, axial and radial forces F are generated on the screw flight 29_R.A. The side 34 of the screw flight 29 also has a side diameter 38, which is depicted in more detail in fig. 4. As shown in fig. 2, the first half of the force F on the grooved ring element 13 is by the threaded ring element 23The torsion preventing portion 24 receives. The second half of the force F (transferred on the slotted ring 13) must be borne via an imbalance of forces on the side 34 of the screw flight 29.

Fig. 4 shows how the second half of the force F according to fig. 2 on the slotted ring 13 is taken up. Fig. 4 shows a schematic view of the force flow. For a better understanding, reference is therefore additionally made to fig. 2 and 3. The surplus torque of the force F on the slotted ring element 13 and the reaction force GF on the anti-twist portion 24 of the threaded ring element 23 is received by the reaction torque generated by the pretension force FV on the slotted ring element 23 in combination with the offset of the axis of rotation R. As long as a new virtual axis of rotation RV remains inside the side 34 of the screw flight 29 during the twisting of the adjusting screw 18, the upper part of the side 34 of the screw flight 29 is not lifted and the adjusting screw 18 is not tilted. Adjusting the inclination of the screw 18 will immediately result in a lost motion on the slotted ring 13. The rotation axis R and the virtual rotation axis RV are spaced from each other by a spacing 40. Additionally, the adjusting screw 18 is automatically centered in the nut thread 35 of the pressure piece 36 during the rotational movement. A deviation of the adjusting screw 18 in the radial direction is thereby avoided. The force F on the grooves 22 of the grooved ring element 13 and the force GF on the anti-rotation section 24 of the threaded ring element 23 are directly related to the pretension force FV. In addition, the slotted ring 13 is stabilized with respect to the guide sleeve 12 via a low supporting force. If the pretension force FV increases, the force F of the slotted ring element 13 and the force GF on the rotation prevention section 24 of the threaded ring element 23 also increase.

A further feature which is evident from fig. 4 is that the distance 37 between the first thread 32 of the screw flight 29 and the force introduction on the slotted ring 13 is between 0 and 1.5 times the lateral diameter 38 of the screw flight 29. Furthermore, the distance 39 between the first thread 32 of the screw flight 29 and the rotation prevention means of the threaded ring 23 is likewise between 0 and 1.5 times the lateral diameter 38 of the screw flight 29. Furthermore, the axial and radial forces F are shown in FIG. 4_R.A。

Fig. 5 shows again in detail how the U-shaped projection 7 of the wrap spring 1 is suspended in the intermediate ring 17. Due to the high forces, special precautions have to be taken with respect to the face-wise load introduction L. The introduction of a point-like load will locally overload the wrap spring 1 and lead to premature failure. To avoid this, the wrap spring 1 is supported in the guide sleeve 12 in the circumferential direction in a three-dimensional shoulder 20 of the intermediate ring 17. This converts the point-like load introduction into the surface-like load introduction L. At the same time, the wrap spring 1 is axially fixed via the shoulder 20.

Fig. 6 shows the arrangement of the wrap spring 1 with its first wrap spring end 2 and its second wrap spring end 3 on the adjusting screw 18. The adjusting screw 18 has a screw thread 29, wherein the coiled spring 1 is arranged directly in the screw thread 29. The first end 2 of the wrap spring extends in the screw thread 29 over an angle α of 90 ° in the circumferential direction and serves to fix the wrap spring 1 on the adjusting screw 18. This prevents the wrap spring 1 from lifting up in the detent position. The clamping position can be seen in fig. 2 and is the area in which the U-shaped projection 7 bears on the shoulder 20 of the intermediate ring 17. The coefficient of friction in the screw flight 29 is between 0 and 0.2.

Fig. 7 shows a representation of a disc brake 200 for a commercial vehicle with a partial view of a hold-down device 260. The disc brake 200 according to fig. 7 has a brake caliper 202 and a brake carrier 201. The brake caliper 202 is configured as a sliding caliper. Furthermore, the disc brake 200 has a first lining carrier 203a and a second lining carrier 203b for holding

friction linings

204a, 204 b. The first lining carrier 203a and the first friction lining 204a are referred to as a first brake lining 212. The second lining carrier 203b and the second friction lining 204b are referred to as a second brake lining 213. The pressing system 211, which comprises the first pressing spring 205a, the second pressing spring 205b and the pressing clip 206, prevents the

brake linings

212, 213 from sliding out in the radial direction. In the case of an actuation of the brake, the

brake linings

212, 213 are pressed against, i.e. pressed against, a brake disk, not shown, by the pressing device 260. The pressing device 260 includes a rotating lever 261 for pressing the

brake pads

212, 213 and a readjustment device 220 for adjusting the clearance between the brake disc and the

brake pads

212, 213.

List of reference numerals

1 coiled spring

2 first end of coiled spring

3 second end of coiled spring

4 wound spring section

5 coiled spring axis

6 first turn of coiled spring

Second turn of 6a coiled spring

7U-shaped convex part

8 disc spring

9 briquetting

10 reconditioning device

12 guide sleeve

13 grooved ring element

14 torsion spring

16-opening ring-shaped piece

17 intermediate ring element

18 adjusting screw

20 shoulder of intermediate annular member 17

21 follow-up side of the guide sleeve 12

22 groove

23 threaded ring

24 anti-twist part

25 angular range

27 first groove side of the grooved ring 13

27a second groove side of the grooved ring element 13

Readjusting pin for 28 turning levers

29 screw thread of the adjusting screw 18

First spiral of 32 screw flight 29

34 side of screw thread 29

35 nut screw thread of briquetting 36

36 briquetting

37 pitch of the first spiral 32 of the screw flight 29

38 side diameter

39 second pitch of the spiral 32 of the screw flight 29

40 distance between the rotation axis R and the virtual rotation axis RV

Angle alpha

Profile angle of beta-screw flight 29

L load introduction

Force F

UF circumferential force

FR free running direction

SR Lock Direction

GF reaction force

F_R.AAxial and radial forces

Reaction force of FN anti-twist portion 24

FV pretension force

R axis of rotation

RV virtual rotation axis

List of reference numerals of the disc brake according to fig. 7

200 disc brake

201 brake carrier

202 brake caliper

203a first liner carrier

203b second liner carrier

204a first friction lining

204b second friction lining

205a first compression spring

205b second compression spring

206 pressing clamp

211 pressing system

212 first brake lining

213 second brake lining

220 reconditioning device

260 pressing device

261 rotating rod

Claims

1. Readjustment device (10) for readjusting the wear of a brake lining of a disc brake, wherein the readjustment device (10) comprises:

a) a guide sleeve (12) in which a coiled spring (1) is arranged,

b) a slotted ring (13) having a slot (22) which surrounds the guide sleeve (12), wherein the slotted ring (13) is coupled to a disk spring (8) via a torsion spring (14),

c) an open ring-shaped element (16) surrounding the slotted ring-shaped element (13),

d) an intermediate ring element (17) for overcoming an air gap between the guide sleeve (12) and the coiled spring (1), and

e) a threaded ring element (23) having an anti-twist portion (24),

wherein the readjustment device (10) is pushed axially over a rotatable adjusting screw (18) of the disc brake, and the adjusting screw (18) has a screw thread (29), characterized in that the wrap spring (1) has a wrap spring first end (2) and a wrap spring second end (3), together with a wrap spring section (4) arranged between the wrap spring first end (2) and the wrap spring second end (3), and the coiled spring section (4) extends axially around a coiled spring axis (5) and has at least one coiled spring turn (6, 6a), wherein the coiled spring (1) has at least one U-shaped projection (7), and is arranged with the U-shaped protrusion (7) on a shoulder (20) of the intermediate ring (17).

2. A readjustment device (10) for readjustment of wear of brake pads of a disc brake according to claim 1, characterized in that the coiled spring (1) is arranged in a screw thread (29) of the adjustment screw (18).

3. A reconditioning apparatus (10) for reconditioning wear of a brake pad of a disc brake according to claim 1 or 2, wherein during a reconditioning process, said wrap spring (1) is supported on a projection (21) of said guide sleeve (12) in a locking direction (SR) opposite to a free-running direction (FR).

4. A reconditioning device (10) for reconditioning wear of a brake pad of a disc brake, according to any of claims 1-2, wherein a torsion prevention portion (24) of the threaded ring (23), a U-shaped protrusion (7) of the wrap spring (1), and a groove (22) of the grooved ring (13) are arranged on one side of the adjustment screw (18) and on the same side.

5. A reconditioning device (10) for reconditioning wear of a brake pad of a disc brake, according to claim 4, wherein a torsion prevention portion (24) of said threaded ring (23), a U-shaped protrusion (7) of said wrap spring (1), and a groove (22) of said slotted ring (13) are arranged within an angular range (25) emanating from said wrap spring axis (5) from 0 to 45 degrees or from 0 to 25 degrees.

6. Disc brake for vehicles, characterized in that it has a reconditioning device (10) according to any one of claims 1 to 5.